Note:

This is not legal advice. This is my opinion, nothing more. If you want legal advice, hire a lawyer.

Why aren’t WordPress themes automatically covered by the GPL?

There’s been a firestorm brewing in the relatively small world of WordPress premium theme designers, after WordPress founder Matt Mullenweg broadly asserted that themes built to run on the WordPress platform – and by implication, plugins and anything else that hooks into the WordPress system – are covered by the GPL.
This is important, because if Matt is correct, then anyone who gets a copy of a premium theme then has the right to freely distribute it or modify it virtually without restriction (expect, of course, those restrictions found in the GPL itself). Understandably, even though some voluntarily release their themes under the GPL, many premium theme designers object to having their code distributed for free.

Matt, who is an outspoken proponent of open-source software, has explained that designers can still make money off GPL code by providing support and other valuable resources to users of that code. And he’s right – that model exists, and has been shown to work for some.

Are premium theme designers “evil”?

But he also goes so far as to call non-GPL premium WordPress themes “evil” – naming Chris Pearson’s Thesis as one such example. Now, I own a Thesis developer’s license and run several sites on the theme. I was happy to pay for it and would do so again. I also know Matt and have considered him a friend for several years now. I commend him for his support of open software and for the impact he’s had on the weblog community.

So it’s tough to say this: Matt, you’re wrong. Not only are these developers not “evil,” they provide a definite benefit to the community. And perhaps more important, the WordPress GPL does not, in most cases, require them to release their own themes or plugins under the GPL.

The argument for an expansive GPL

The template is loaded via the include() function. Its contents are combined with the WordPress code in memory to be processed by PHP along with (and completely indistinguishable from) the rest of WordPress. The PHP code consists largely of calls to WordPress functions and sparse, minimal logic to control which WordPress functions are accessed and how many times they will be called. They are derivative of WordPress because every part of them is determined by the content of the WordPress functions they call. As works of authorship, they are designed only to be combined with WordPress into a larger work.

In other words, the code created by theme developers, because it works together with WordPress code (and in most cases, cannot function without it) is a “derivative work” of WordPress under copyright law and therefore falls within the scope of the GPL. (The GPL, as a copyright-based license, applies only to the original work and those works that derive from it.) At least, that’s the argument.

The counter-argument to an expansive GPL

But is it enough to say that a theme calls to WordPress functions or that it is somehow “combined with WordPress code in memory”? Does that make it a derivative, and therefore covered, work under the law and the GPL?

There are plenty of reasons to disagree with the expansive GPL view expressed above. First and foremost, it’s just not enough to say that themes running on top of, and using function calls from, a piece of software are “derivative” of that software. If that were the case, then any software application would be a derivative work of the operating system it runs on – such as Windows, Linux, or OS X – which in turn would be a derivative work of the software hard-coded into the chips running the computer. For that is the way all software works, down to the bare iron – it sits on top of, and makes function calls to, the software layer beneath it, until to get down to the silicon pathways in the chip itself. No software could run without those lower layers, and nothing is truly independent of them. But “dependent” and “derivative” are not the same thing.

Instead, copyright law takes a very pragmatic approach to determine what constitutes a derivative work.

The alleged derivative must “physically incorporate a portion of a copyrighted work… [or] supplant demand for a component of that work.”

In the case of Lewis Galoob Toys, Inc. v. Nintendo of America, Inc., 964 F. 2d 965 (9th Cir. 1992), a federal appellate court considered that very issue. Galoob manufactured a “cheater” cartridge that plugged into Nintendo games, between the game cartridge and the game unit itself, and allowed the player to change the game’s parameters – for example, players could give themselves unlimited lives using Galoob’s device. Nintendo sued Galoob, claiming that the devices violated Nintendo’s copyright in the games as a derivative work of the games.

The Galoob court rejected Nintendo’s argument. In order to be considered a derivative work, the alleged derivative must “physically incorporate a portion of a copyrighted work… [or] supplant demand for a component of that work.” Galoob at 969. Finding that Galoob’s device did neither, the court determined that there was no derivative work.

An important part of the court’s analysis was that “technology often advances by improvement rather than replacement.” Id. The court also noted that software often depends on other software to function:

Some time ago, for example, computer companies began marketing spell-checkers that operate within existing word processors by signalling the writer when a word is misspelled. These applications, as well as countless others, could not be produced and marketed if courts were to conclude that the word processor and spell-checker combination is a derivative work based on the word processor alone.

The Game Genie is useless by itself, it can only enhance, and cannot duplicate or recaste, [sic] a Nintendo game’s output. It does not contain or produce a Nintendo game’s output in some concrete or permanent form, nor does it supplant demand for Nintendo game cartridges. Such innovations rarely will constitute infringing derivative works under the Copyright Act.

Using that rationale, the question of whether WordPress themes are “derivative” of WordPress itself becomes more clear.

Does a theme, rather than simply calling a WP function, incorporate actual code from WordPress?

Does it somehow supplant the demand for the WordPress software itself?

If the answer to either of those questions is “yes,” then the work is probably derivative, and the GPL probably applies. If not, then even a theme or plugin that entirely dependens on WordPress to run at all, or simply improves WordPress in some way, would not be a derivative work and the GPL would not apply. For the vast majority of themes I’ve seen, the GPL would not apply because the theme is not, in my opinion, a derivative work. (In fact, if any one thing “incorporates” another, it’s most likely WordPress incorporating the theme, by use of the PHP include() call, rather than the other way around.)

Should the GPL apply to premium WordPress themes?

Matt’s own experience with WordPress is a very convincing argument that it is possible to change the world, or even just make a living, by writing, distributing, and supporting GPL-based software. There are many premium theme designers – promoted and catalogued by WordPress – who choose to apply to GPL to their own labors. But those who choose not to? Not evil – at least not for that reason.

It’s great to talk about open source software as “free” and speak of the GPL – as Matt does – as a “Bill of Rights” – but what Matt seeks to do would reduce freedom by expanding copyright restrictions to non-derivative – and therefore legally independent – works . At its core, the GPL is simply a fancy way of controlling other people’s work through the imposition of copyright restrictions. Those who seek to extend the GPL beyond the bounds allowed by copyright law, do not promote freedom but instead take freedom away.

Update: What WordPress itself says about derivative works and copyright law

a “work based on the Program” means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language.

(Emphasis added.) In other words:

Copyright law controls the definition of what constitutes a “derivative work” (and therefore, a covered work); and,

The GPL expressly invokes the standard embraced by the Galoob court, namely, that some part of the original work must be contained in another work in order for that work to be considered derivative.

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Leo, I enjoy your Zenhabits blog, but you should stick to your last (which is neither software, nor law). You keep pulling the matter into a run-time context, while it really is a distribution-time issue. But I admire you for doing that with so much passion – even if you are completely wrong.